New stick insect species discovered in Queensland named Australia’s heaviest

Scientists identify Acrophylla alta in Queensland rainforest, marking it as Australia’s heaviest insect at 44 grams.

In the dense canopies of a remote rainforest in Far North Queensland, Australia, scientists have uncovered a remarkable new species of stick insect — believed to be the heaviest ever recorded in the country. Weighing in at 44 grams (1.55 oz) and stretching 40 centimeters (15.75 inches) in length, the newly identified Acrophylla alta rivals the weight of a golf ball.

Scientists have discovered a giant new species of stick insect in Australia, which is over 15 inches long and researchers say may be the heaviest insect in the country. pic.twitter.com/y0E0r58Olg

— ABC News (@ABC) July 31, 2025

James Cook University’s Professor Angus Emmott, who was part of the discovery team, attributes the insect’s large size to its cool, wet environment. “Their size likely helps them survive the colder conditions, and that's why they've developed into this large insect over millions of years,” Emmott explained in a university media release. “From what we know to date, this is Australia's heaviest insect.”

The insect was found in the Wet Tropics of Queensland, a high-altitude rainforest region known for its biodiversity and ecological isolation. Emmott noted that the insect’s secluded habitat likely explains why it has eluded discovery until now. “It lives high in the canopy. So, unless you get a cyclone or a bird bringing one down, very few people get to see them,” he said.

One of the critical identifiers for this new species was its uniquely patterned eggs. “Every species of stick insect has their own distinct egg style,” Emmott said. “They’ve all got different textures, shapes, and even unique caps.”

Two specimens have already been added to the Queensland Museum’s collection, aiding future research into this rare insect and its ecosystem.

The discovery is a major addition to Australia’s biodiversity and highlights the importance of preserving fragile rainforest environments that may still hold more hidden species.